Method of producing composite



Sept. 25, 19340 D. J. CAMPBELL METHOD OF PRODUCING COMPOSITE BRAKE DRUMS Filed June 8. 1931 STATES PATENT OFFICE METHOD OF PRODUCING COMPOSITE BRAKE DRUMS Donald J. Campbell, Muskegon Heights, Mich,

assignor to Campbell, Wyant & Cannon Foundry Company, Muskegon Heights, Mich, a corporation of Michigan Application June 8, 1931, Serial No. 542,73?

" 3 Claims ill. 29=-l52.2)

This invention relates to a composite brake An understanding of the invention for the drum structure and method of producing the attainment of the ends stated may be had from same. the following description, taken in connection I have heretofore filed application for patent, with the accompanying drawing, in which,

Serial No, 512,792, filed February 2, 1931, relating Fig. 1 is an elevation of the completed brake 'to the centrifugal depositing of molten cast iron drum.

at the inner side of an annular band of a brake Fig. 2 is a fragmentary enlarged section throng or other cylindrical structure, preformed one side of the two members of the brake m into shape and in readiness to receive the cast prior to their being brazed together.

m iron when it is deposited thereagainst. With Fig. 3 illustrates the two members of the brake such process of centrifugal casting the inner lindrum with the cast metal lining within the outer ing band of cast metal against the drum. has a member and the bracing member located in place substantiallyintegral fused connection of the two prior to the introduction thereof into a furnace, metals produced at their juncture, which insepand t m arably joins the cast metal lining to the outer Fig. 4 illustrates the completed braaeddrum pressed, rolled or otherwise formed band or with the lining having a brazed and, in client,

With the present invention it is an object and integral connection with the outer member. purpose thereof to cast the band separate from Like reference characters refer to like parts the preformed drum, machine at its outer side so in the different figures oi the drawing. m that it will have a slightly larger diameter than The outer brake drum member, rolled, presse 755 the inner diameter of the annular band of the or otherwise formed from metal has a continubrake to which it is to beapplied, 'thereous annular band 1 connected with a back or after heating the brake band either before web 2. In practice the band at its free edge is or after it is welded to the hacker web or the many times formed with a reinforced and 253 so that the cast metal band may be received strengthening flange 3 though so far as the intherein, whereby with cooling the brake drum vention is concerned this flange is not needed band it will we upon the cast metal lining nor required. Many times the annular section and very tightly connect therewith. This alone, 1 oi the drum is formed separately from the web however, is not suflcient to provide the necesor back 2, and later they are'welded together; sary connection between the cast metal and and my invention may be utilized either before the pressed, rolled or formed metal especially as or after the annular section 1 is connected to in the use of the drum in an automobile, severe the back or web 2. The lining d of cast metal, heat and high degrees of temperature are genpreferably cast iron, is east in a suitable mold erated by the friction of the brakes against the in an annularring-like form and with my inven- 35 brake This expands the metals, and the tion is machinedat itsouter side so that it will 99 same having diilerent c'oeflicients of expansion have an exterior diameter slightly larger than are quite liable to separate, and in addition the the inner diameter of the part 1 of the outer strains to which the brake drum is subjected in member at normal atmospheric temperatures. service may cause deformation of the outer pre- In order that the cast metal lining may be informed member of the drum and cause a sepaserted within the part 1, said part 1 or, if it ration thereof from the inner cast metal band. has been welded to the back 2, the entire outer Therefore, it is a further object and purpose member of the drumis heated to a sufliciently of my invention to in eflect braze the two parts high degree of temperature that it will be exof th b ke -u:' 1:" .together, using a suitable pended so that the inner diameter of the section 45 brazing metal which may be laid at the outer 1 is greater than the outer diameter of the coldedges of the joint between the cast metal lining er cast metal band 4 which may then be inserted and the outer drum member, subjecting the whole in place. This is illustrated in Fig. 3-. to heat and a high degree of temperature in a At the joint at the outer edge of the lining suitable ice, such as an electric furnace, 4 between it and the surrounding section 1 or whereupon the brazing material is melted and the outer drum member, asuitable brazing matepasses between the two members of the drum rial, copper or its equivalent, is laid preferably fiovnng and making an intimate binding or brazin the form oi a wire indicated at 5. The drum mg connection of the two which for practical with the wire thus positioned is then placed in purposes renders the two parts or members of a. furnace and the whole heated to a temperature 55 the brake drum construction in effect integral. such that the copper wire 5 or other equivalent brazing material melts and passes into the joint between the lining and the outer drum section 1. No large quantity of the brazing material is required because of the very. tight, in fact shrink fit of the part 1 around the cast metal band. Any and all interstices between the two parts are filled with the melted brazing material and a complete bond between the lining and the outer member of the brake drum is made.

This invention produces very satisfactory brake drums with an'insurance that the inner lining of cast metal will not separate from the outer member at any point which, if it occurs, results in cracking of the inner lining due, it is believed, to the development of very high temperatures in the lining, as the heat cannot escape therefrom if there is anything less than in effect an integral connection between the inner band and the outer member of the drum. The brazing process herein described provides such connection allowing the escape of heat. Furthermore, the bond between the lining and the outer member of the drum serves to insure against anyrotative movement of one with respect to the other and also that the outer pressed or rolled member of the construction will not separate from the lining of cast iron through distortion due to strains to which a brake drum is subjected in service.

The invention while it has been described specifically as applied to automobile brake drums is in no sense limited exclusively thereto but is to be considered applicable in all places of use where it can be used and to comprehend all forms of structure coming within the scope of the invention as defined by the appended claims.

I claim:

1. The process of making brake drums which consists, in providing a continuous annular outer band formed of sheet metal with the inherent irregularities therein, casting a continuous annular band, machining the same at its outer side to provide a band having an exterior diameter slightly greater than the least interior diameter of said continuous outer band, heating the outer band to expand the same, inserting the cast band therewithin, placing a metal of comparatively low melting point above the juncture between the outer band and the said amnular band, and thereafter subjecting the. composite structure to heat sufiicient to melt the said metal whereby the same flows downwardly between the two bands and completely fills the irregular space therebetween for the purpose described.

2. The herein described method of producing a brake drum which comprises, forming an outer annular continuous drum flange from metal adapted to be pressed or rolled into shape, inserting a cast metal band within the drum flange, said cast metal band having a greater normal exterior diameter than the inner normal diameter of the said drum flange, applying a brazing metal at the joint between the said drum flange and inner band, and subjecting all to heat treatment whereby the brazing metal is melted and fills interstices between the flange and inner band and provides a brazing connection between said flange and inner band whereby an even and uniform heat flow is had therethrough.

3. The herein described method of producing,

a brake drum which comprises, forming an outer annular continuous drum flange from steel sheet metal adapted to be pressed or rolled into shape, heating the drum flange and inserting a cast metal band of cast iron within the drum. flange, said cast metal band having a greater normal exterior diameter than the inner normal diameter of the said drum flange, applying copper at the joint between the said drum flange and inner band, and subjecting all to heat treatment whereby the copper is melted and fills interstices between the flange and inner band and whereby an even and uniform heat flow is had therethrough.

DONALD J. CAMPBELL. 

